While figuring out how to send mankind to Mars might be the hot topic of the day, there are still plenty of problems to solve on Earth, not least those presented by various humanitarian crises erupting across the globe. That's where the Aid Innovation Challenge comes in.

Part of the annual global humanitarian and development aid event AidEx, it is a Dragons' Den-style competition aimed at finding the next big invention that can help improve the way aid is delivered.

Here are the four finalists from this year's competition who will be taking to the stage in Brussels on November 16.

The problem: Finding access to clean drinking water is one of the biggest problems during an emergency crisis. International guidelines suggest that each person should receive between 7.5 and 15 liters a day to cover their basic needs. However meeting these minimum standards is often difficult water sources sometimes miles away, and refugees lacking the means to store water at their shelters. Conventional water tanks, while useful, are expensive and heavy, and do not lend themselves to an agile setup.